JPH0485112A - Pneumatic tire for travelling on icy/snowy road surface - Google Patents

Abstract

PURPOSE:To improve spinning traction performance, braking performance, and the like on ice by setting the sipe spacing of a center block narrower than that of a side block, dividing the center block circumferentially into two by a width direction separated sipe, and further dividing each half block part into two in the width direction by a circumferential thin groove. CONSTITUTION:The spacing of the sipes 7 of a center block 3 is set narrower than that of the sipes 8 of a side block 4. The center block 3 is circumferentially divided into two by a cut-off sipe 9 extended in the tire width direction. Each half block part is further divided into two in the tire width direction by a circumferential thin groove 10. In this case, the thin grooves 10, 10 formed at the respective block parts are mutually offset in the width direction by the distance (e). The center block 3 and the side block 4 are both formed into a contour shape of width direction line segments and broken lined circumferential line segments, and the number of the contour corner parts 5 of the center block 3 is to be more than that of the contour corner parts 6 of the side block 4.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to a studless type pneumatic tire that has a low coefficient of friction and is useful for icy and snowy road surfaces, and is used for general driving on icy and snowy roads. Not only does it exhibit high braking performance, traction performance, and control performance, but it is also used in winter rally competitions and exhibits extremely excellent maneuverability even on tracks close to the ice.

(Prior Art) As a prior art related to tires used for running on snowy and/or icy roads, especially studless tires for rally use, there is, for example, one disclosed in Japanese Patent Application Laid-Open No. 63-275408. attempts to improve braking performance, traction performance, and control performance, especially on snow-packed roads, by forming a block pattern that satisfies predetermined conditions on a tread made of rubber with a specific hardness. .

In addition, here, each of the central area block rows and side area block rows formed in the central area in the tread width direction and the respective side areas sandwiching this central area is provided with blocks extending in the tread width direction and forming the tire. When a plurality of sipes are formed with a groove width such that the groove walls come into contact with each other during load transfer, wear resistance is In order to ensure the same level, the sipe intervals of each block are set relatively large.

(Problem to be Solved by the Invention) For this reason, in the tire of this prior art, the number of sipe edges present in the contact patch is relatively small, but according to subsequent research by the inventor, the number of sipe edges in the contact patch is relatively small. It was found that increasing the number of ice has a large effect on spinning traction performance on ice and braking performance on ice.

Therefore, in order to improve the performance of each of them, it is preferable to increase the number of sipes, but as mentioned above, this also has the problem of lowering the wear resistance. Since the block rigidity differs between the block and the center block even under the same human power, an increase in the number of sipes in the side block in particular causes a significant decrease in wear resistance due to the decrease in block rigidity. was there.

Furthermore, since there is a difference in the input level that acts on the side blocks and the center block during tire transfer, when the sipe spacing of both is the same, the rigidity of the side blocks and the center block is Even if both blocks were the same, there would be a difference in the amount of deformation between them, and the movement of each block within the ground plane would not be uniform, causing problems in motion performance, especially control performance.

The present invention advantageously solves the problems of the prior art, and increases (improves) on-ice spinning traction performance, on-ice braking performance, and control performance without reducing wear resistance. To provide a pneumatic tire for driving on icy and snowy roads.

(Means for Solving the Problem) As a result of various studies, the inventor discovered that both spinning traction performance on ice and braking performance on ice are greatly influenced by the number of sipe edges in the tread contact surface, mainly in the center block. In addition, the sipe spacing of the center block was narrower than similar sipe spacing in the prior art, while the sipe spacing of the side blocks was
It has been found that by using the same spacing as in the prior art, it is possible to greatly improve each of the above-mentioned performances and still sufficiently prevent a decrease in wear resistance.

Therefore, in the pneumatic tire for running on icy and snowy roads of the present invention, each central block is divided into two halves on the treading side and the kicking side by a separation sipe extending in the tread width direction, and each of these halves When it is further divided into two in the tread width direction by a thin groove extending in the circumferential direction,
Preferably, the spacing between the sipes formed in the center block is narrower than that of the sipes formed in the side blocks, and each of the center block and the side blocks is preferably connected to a line segment extending in the tread width direction and a tread circumference. The contour shape is surrounded by broken lines extending stepwise in the direction, and the number of contour corners including the outer and inner corners of the central block is larger than the number of contour corners of the side blocks.

(Function) In this pneumatic tire, the sipe spacing in each center block is made narrower than the sipe spacing in each side block to increase the total number of sipes in the contact patch, and to increase the number of sipes in that plane to the side blocks. By increasing the number of block rows in the center area than in the area block rows, firstly, as mentioned above, both on-ice spinning traction performance and on-ice braking performance can be significantly improved, and secondly, the rigidity of the side blocks can be improved. is larger than that of the center block, we can calculate the difference in the amount of deformation of each block due to the load acting on the side blocks being greater than the load acting on the center block when the vehicle is turning. This is made sufficiently small to improve control performance, especially on icy and snowy roads, and thirdly, when turning on dry roads, the block input during load transfer is larger on the side blocks than on the center block. As a result, even if the sipe spacing of the center block is narrower than that of the side blocks, there is almost no difference in the degree of wear between the two blocks;
Uniform wear of the entire tread surface can be promoted.

In addition, each center block has a contour shape surrounded by line segments extending in the tread width direction and broken lines extending stepwise in the tread circumferential direction, and sipes extending from the inner corners of the center block in the tread width direction, If the number of protruding corners of the center block is increased by forming the sipes at intervals narrower than those of the side blocks, the amount of movement of the sipe edges when the tire rolls under load will be increased, greatly improving on-snow performance. can be improved.

Here, by dividing at least each central block into two parts, the tread side and the kick-off side, by separating the sipes, it is possible to ensure appropriate block rigidity in the tread circumferential direction. By further dividing each half into two in the tread width direction by a narrow groove, the block stiffness in the tread width direction is advantageously reduced, reducing the difference in stiffness between the center block and the side blocks, and increasing the By making the movement of each block almost uniform, control performance can be further improved.

In addition, each block halves, which are divided into two in the tread width direction by the narrow grooves, can deform more freely when contacting the ground, and can more effectively bring out the edge effect due to the opening and closing of the sipes. By increasing the sideslip resistance, it is possible to sufficiently increase sideslip resistance, and as a result, it is possible to more effectively improve the spinning trough performance and side grip performance required for rally competitions.

Furthermore, when each of the center block and side blocks has a contour shape surrounded by line segments extending in the tread width direction and broken lines extending stepwise in the tread circumferential direction, the number of contour corners of the center block is , more preferably than that of the side blocks, more preferably 35-45 of the central block and 20-3 of the side blocks.
By setting the range to 0, the block edge effect on snow and ice will be enhanced and the sipes connecting the corners will be activated, so the number of contour corners of the center block can be increased by increasing the number of contour corners of the side blocks. By doing so, it is possible to effectively bring out the sipe edge effect associated with block edge activation, and in combination with securing the number of sipes mentioned above, on-ice traxilon performance and braking performance are further improved.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a developed view of a tread showing an embodiment of the present invention.

The internal structure of the tire is the same as that of a radial tire for boat fishing, so illustration is omitted here.

In the figure, 1 indicates a center region block row formed in the center region in the tread width direction, 2 indicates a side region block row formed in each side region sandwiching the tread center region, and 3.4 denote the central block and side blocks forming their respective block rows, respectively;
These blocks 3.4 are located approximately in a staggered manner in the tread width direction.

Here, each of the center block 3 and the side blocks 4 has a contour shape surrounded by a line segment extending in the tread width direction and a broken line extending stepwise in the tread circumferential direction. The total number of contour corners 5 including the outside corners and inside corners is in the range of 35 to 45, and the total number of the contour corners 6 of the side block 4 is in the range of 20 to 30.

Each of the blocks 3 and 4 is formed with a plurality of sipes 7.8 extending from each corner of the block in the tread width direction and opening at both ends of each block. The interval between the sipes 7 is made narrower than the interval between the sipes 8 formed on the side block 4. Here, each size 7.8 has a groove width such that the groove walls contact each other during load transfer of the tire, for example, a groove width of 0.3 to 1.0.

Although at least each central block 3 extends in the tread width direction and has a groove width somewhat wider than each sipe 7.8 described above, for example, 1.0 to 2.0 m, the load on the tire is At the time of transfer, the groove walls are roughly divided into three equal parts by the separating sipes 9 that contact each other into two halves on the stepping side and two halves on the kicking side, and each of these halves is further divided into two halves in the tread width direction by narrow grooves 10 extending in the circumferential direction of the tread. Divide into two. Here, since the two halves of the center block 3 on the stepping side and the two halves on the kicking side have a so-called point symmetrical shape, each of the narrow grooves 10 is offset by a distance e in the tread width direction.

Furthermore, in this example, the outer g! of each side block 4! At the end, there are grooves 11 that function to improve steering stability when driving in ruts, and the blocks 4 are formed with narrow crank grooves 12 that extend stepwise in the circumferential direction of the tire, which also improves the tread width. Bisect in two directions.

By the way, although it is not clear from the figure, the depth of each sipe 7.8 can be made uniform over its entire length, and the depth of each sipe 7.8 can be made uniform over its entire length, as well as the depth of each sipe 7. By making the grooves particularly shallow in the vicinity of the two halves of the grooves 10° and 12 and applying some restraint to the movement of the sipe edge, it is possible to provide block rigidity that is advantageous for improving traction performance and braking performance.

According to the tire configured as described above, the separation sipes 9 and the narrow grooves 10 provided in each central block 3 activate the movement of each of the square blocks constituting the central area block, and Since activation of the block edge via the circumferential narrow groove is ensured even in response to lateral human force, both traction performance and lateral grip level are improved, and controllability is improved. Also, central block 3
By making the sipe spacing narrower than that of the side block 4, as mentioned above, the traction spinning performance on ice, the braking performance on ice, and the control performance on ice and snow road surfaces are sufficiently improved, and uneven wear resistance is achieved. The properties can also be advantageously improved.

Furthermore, by extending each sipe of the central block 3 from its inner corner position in the tread width direction, the amount of displacement of the sipe edge is increased, which also greatly improves on-snow performance, as described above. be able to.

In addition, in the illustrated example, the side block 4 is provided with a crank narrow groove 12.
By dividing the tread width into two in the tread width direction, the same effect as the center block can be obtained.By creating a crank shape, the narrow grooves avoid an extreme decrease in block rigidity, and maintain appropriate block rigidity against input. secure.

[Comparative example]

Comparative tests of the lap time, grip level, and control performance of the invention tire and conventional tire when running on an actual vehicle on various road surfaces, as well as the wear resistance during actual vehicle running on a dry paved road will be described below.

◎Test tire/invention tire Size 195 with the tread pattern shown in Figure 1
/65 R15 tire with a 4-1 sipe spacing in the center block and a 5-layer sipe spacing in the side blocks ・Conventional tire A tire with a tread pattern shown in Figure 2, with a sipe spacing of 4-1 in the center block and a 5-layer sipe spacing in the side blocks. The size, rubber quality, etc. were the same as the invented tire, except that the sipe spacing of the block and the sipe spacing of the side blocks were both set to 5. .0 kg
f/am” and a load of 505 kg, we investigated lap times, grip levels, and control performance when driving on fresh snow or soft compacted snow roads and hard compacted snow or icy roads, and also investigated the wear level on dry paved roads. investigated.

The grip level and control performance were evaluated by the feeling of the test driver, and the wear level was evaluated by visual inspection.

◎Test Results The results of each test are shown in the table below as an index using conventional tires as a control.

Here, Table 1 shows the results on fresh snow or soft snow roads.
Table 2 shows the results on hard compacted snow and icy roads, respectively, and Table 3 shows the results on the wear level.

It should be noted that the larger the index in Table 1.2, and the smaller the index in Table 3, the better the result.

Table 1 Table 2 Table 3 According to these tables, the invented tire showed much better results than the conventional tire in terms of lap time, grip level, and control performance on icy and snowy roads under various conditions, and among them, grip It is clear that the level of results is excellent and, moreover, the wear resistance is not reduced.

(Effects of the Invention) Thus, according to the present invention, as is clear from the above comparative example, extremely excellent maneuverability is exhibited on various running roads with a low coefficient of friction, from freshly snowy roads to icy roads. be able to.

[Brief explanation of drawings]

FIG. 1 is a developed tread diagram showing an embodiment of the present invention, and FIG. 2 is a developed tread diagram showing a conventional example. 1...Central area block row 2...Side area block row 3...Central block 4...Side block 5.6...Outline corner 7, 8...Sipe 9.
... Separation sipe 10 ... Narrow groove 11 ... Recessed part 12 ... Crank narrow groove Fig. 1

Claims (1)

[Scope of Claims] 1. A central area block row and a side area block row formed in a central area in the tread width direction and respective side areas sandwiching the central area; A tire comprising a plurality of sipes extending in the tread width direction and opening at both ends of each block in each center block and each side block in the row of side area blocks, wherein each center block The central block is divided into two halves on the stepping side and the kicking side by a separation sipe extending in the tread width direction, and each half is further divided into two in the tread width direction by a narrow groove extending in the tread circumferential direction. A pneumatic tire for running on icy and snowy roads, in which the spacing between the sipes formed on the side blocks is narrower than that of the sipes formed on the side blocks. 2. Each of the center block and side blocks has a contour shape surrounded by line segments extending in the tread width direction and broken lines extending stepwise in the tread circumferential direction, and the number of contour corners of the center block is The pneumatic tire according to claim 1, wherein the number of the blocks is greater than the number of contour corners of the blocks.